• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권11호
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• pp.3030-3049
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• 2023

With the development and wide application of hybrid network computing modes like cloud computing, edge computing and fog computing, the customer service requests and the collaborative optimization of various computing resources face huge challenges. Considering the characteristics of network environment resources, the optimized deployment of service resources is a feasible solution. So, in this paper, the optimal goals for deploying service resources are customer experience and service cost. The focus is on the system impact of deploying services on load, fault tolerance, service cost, and quality of service (QoS). Therefore, the alternate node filtering algorithm (ANF) and the adjustment factor of cost matrix are proposed in this paper to enhance the system service performance without changing the minimum total service cost, and corresponding theoretical proof has been provided. In addition, for improving the fault tolerance of system, the alternate node preference factor and algorithm (ANP) are presented, which can effectively reduce the probability of data copy loss, based on which an improved cost-efficient replica deployment strategy named ICERD is given. Finally, by simulating the random occurrence of cloud node failures in the experiments and comparing the ICERD strategy with representative strategies, it has been validated that the ICERD strategy proposed in this paper not only effectively reduces customer access latency, meets customers' QoS requests, and improves system service quality, but also maintains the load balancing of the entire system, reduces service cost, enhances system fault tolerance, which further confirm the effectiveness and reliability of the ICERD strategy.

• 한국군사과학기술학회지
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• 제19권4호
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• pp.443-452
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• 2016

Current low-altitude radar system often fails to detect small unmanned aerial vehicles (UAV) because of their small radar cross section (RCS) compared with larger targets. As a potential alternative, a passive bistatic radar system has been considered. We study an optimal deployment problem for the passive bistatic radar system. We model this problem as a covering problem, and develop an integer programming model. The objective of the model is to maximize coverage of a passive bistatic radar system. Our model takes into account factors specific to a bistatic radar system, including bistatic RCS and transmitter-receiver pair coverage. Considering bistatic RCS instead of constant RCS is important because the slight difference of RCS value for small UAVs could significantly influence the detection probability. The paired radar coverage is defined by using the concept of gradual coverage and cooperative coverage to represent a realistic environment.

• 한국정보통신학회논문지
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• 제17권4호
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• pp.847-856
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• 2013

본 논문에서는 실내 환경에서 위치 인식을 고려한 AP 배치 기법을 제안하고 성능평가를 수행하였다. 제안한 기법은 위치 인식율과 AP 기반 무선 네트워크의 성능 및 비용을 고려하여 근사 최적 AP 구성 형태를 생성하는 메타휴리스틱 알고리즘과 AP 배치 과정을 빠르게 수렴하게 하는 결정론적 알고리즘으로 구성된다. 실내 공간과 유사한 시뮬레이션 환경을 구축하여 제안한 AP 배치 기법의 성능 평가를 수행하였으며, 제안한 기법은 빠른 시간 내에 우수한 결과를 생성하였다.

• 경영과학
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• 제33권2호
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• pp.75-87
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• 2016

Quality function deployment (QFD) is a widely adopted customer-oriented product development methodology by analyzing customer requirements. It is a main activity in QFD planning process to determine the optimal values of the technical attributes (TAs) so as to achieve the customer requirements (CRs) from the House of Quality (HoQ). In most of the previous research, all the TAs in QFD are assumed to have either continuous or discrete values. In the real world applications, the continuous TAs and the discrete TAs are often mixed in QFD. In this paper, a mixed integer linear programming model is formulated to obtain the optimal values for the continuous TAs and the discrete TAs in QFD planning as well as Branch and Bound (B and B) algorithm is proposed as the solution approach. Finally, the proposed model and solution approach are illustrated with an office chair under multi-segment market, and the sensitivity analysis is performed to study how the proposed model and its solutions respond to the variation for the two elements which are budget and CRs' weights.

• Journal of Electrical Engineering and Technology
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• 제13권5호
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• pp.1769-1777
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• 2018

This paper proposes a method for optimal placement of Phasor Measurement Units (PMUs) considering system configuration and its attributes during the planning phase of PMU deployment. Each bus of the system is assessed on four diverse attributes; namely, redundancy of measurements, rotor angle and frequency monitoring of generator buses, reactive power deficiency, and maximum loading limit under transmission line outage contingency, and a consolidated 'degree of criticality' is determined using Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS). The major contribution of the proposed work is the development of modified objective function which incorporates values of the degree of criticality of buses. The problem is formulated as maximization of the aggregate degree of criticality of the system. The resultant PMU configuration extends complete observability of the system and majority of the PMUs are located on critical buses. As budgetary restrictions on utilities may not allow installation PMUs even at optimal locations in a single phase, multi-horizon deployment of PMUs is also addressed. The proposed approach is tested on IEEE 14-bus, IEEE 30-bus, New England (NE) 39-bus, IEEE 57-bus and IEEE 118-bus systems and compared with some existing methods.

• 한국지하수토양환경학회지:지하수토양환경
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• 제29권4호
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• pp.12-20
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• 2024

Diffusive gradients in thin films (DGT) are passive sampling devices used to determine the time-weighted average concentrations (TWAC) of contaminants. To ensure accurate performance in groundwater, it is crucial to identify environmental characteristics and maintain optimal operational conditions. This study examined the deployment time required to reach effective capacity, the thickness of the diffusive boundary layer (DBL) under stagnant water conditions, and biofilm formation on the DGT surface using groundwater samples. When using DGT with Chelex gel (A=3.14 cm²), the effective capacity was 0.7 ㎍ for Cd and 250 ㎍ for Zn, with a deployment time of 24 h. Lower Cd accumulation was due to the competition effect of coexisting ions. The DBL thickness under stagnant conditions was 0.074 cm, 93% of the diffusion gel's thickness (0.08 cm). Neglecting DBL thickness in TWAC calculations led to a 79% decrease in the determined concentration. No biofouling was observed during the 28-d DGT deployment in groundwater. In conclusion, it is essential to consider the appropriate deployment time, DBL thickness, and biofilm formation to ensure accurate DGT performance in determining contaminant levels in groundwater.

• 한국정보통신학회논문지
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• 제27권1호
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• pp.62-68
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• 2023

무인항공기 또는 드론(UAV or Drone)을 활용한 공중 통신중계기는 재난피해 지역, 군 작전 지역, 응급상황 발생 시 등의 임시 통신 서비스 지원에 활용되고 있다. 무인항공기를 활용한 공중 통신중계기는 원격 사용자 또는 임무 수행자에게 안정적인 통신 서비스를 제공하는 것을 목표로 하므로 최소 성능 요구사항을 보장하는 빠른 무인항공기의 배치가 중요하다. 무인항공기를 통신 시스템에서 활용하는 연구에서는 통신 성능을 극대화하는 무인항공기의 최적위치를 찾는 연구가 대부분이나, 위급상황 시에는 최적 위치보다는 무인항공기 배치 가능 영역을 빠르게 도출하고 통신 지원을 위한 빠른 배치가 더 중요하다. 본 논문에서는 무인항공기를 공중 통신중계기로 활용 시 각 상황에 따라 요구되는 통신 성능을 보장하는 무인항공기 배치 가능 영역을 도출하고, 이론적 분석을 통해 얻은 결과를 시뮬레이션 완전 탐색을 통해 검증하고자 한다.

• 한국군사과학기술학회지
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• 제20권2호
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• pp.197-205
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• 2017

During the sea trial, we discovered EMI between MOSCOS and ES DF antenna. CW emitted by MOSCOS raised the threshold level of ES DF antenna. As a result, direction finding rate of ES has been decreased. This is a study for the improvement of EMI between the antennas mounted on a surface ship. An analysis is accomplished for MOSCOS, ES DF antenna and Jamming transmitter. This paper presents the method how to solve EMI based on the measurements and calculations about the ES DF antenna receiving level, MOSCOS radiation pattern and Jamming transmitter thermal noise. The test was performed with optimal deployment of MOSCOS on a surface ship. After changing the position of MOSCOS, EMI has been decreased significantly.

• 한국시뮬레이션학회논문지
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• 제27권1호
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• pp.39-49
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• 2018

잠수함으로부터 발사되는 SLBM은 은밀성으로 인해 탐지가 매우 제한적이며 이는 안보에 심각한 위협으로 인식된다. 본 연구는 SLBM의 효과적인 탐지를 위한 구축함 배치 최적화 문제를 고려한다. 최적화 모델은 2인 제로섬 게임을 기반으로 하여, 상대방의 입장에서 SLBM이 최대한 탐지되지 않는 발사 및 도착 지점과 비행궤적을 결정하고자 하며, 우리의 입장에서는 상대방의 SLBM 탐지를 최대화할 수 있는 구축함의 배치 계획을 수립한다. 제시된 2인 제로섬 게임 모델은 선형계획법으로 변환하여 최적해를 구할 수 있으며, 가상의 임의 구역과 시나리오를 생성하여 계산 실험을 수행하고 본 연구에서 제시하는 모델을 통해 게임에서의 상대방과 우리의 최적 혼합전략을 도출한 결과를 보여준다.

• 의료ㆍ복지 건축 : 한국의료복지건축학회 논문집
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• 제25권1호
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• pp.29-40
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• 2019

Purpose: The purpose of this study is to analyze the deployment characteristics of korean and foreign mobile hospitals and to draw out the advantages and disadvantages based on the movement of patients. Methods: The arrangement and user movement lines of foreign mobile hospitals which were actually utilized, and the arrangements and user movement lines of korean mobile hospitals are compared and analyzed. Based on the results of the comparative analysis, we suggest the optimal placement of mobile hospital in Korea. Results: The recently developed Korean mobile hospitals have made many improvements. However, there is no practical use case for the mobile hospital in Korea, so it is necessary to establish the basis for the mobile hospital development site and the site access considerations. In addition, there is no detailed analysis of the movement of the administrators other than the medical staff, and it is considered that research on safe waste disposal is further needed. Implications: It is highly likely to be used as a basic data to find out the combination method of mobile hospitals that can efficiently deal with disasters through the arrangement and movement analysis of mobile hospitals in Korea and abroad.